<?php

/**
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements. See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 *
 *	   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 * @package log4php
 */

/**
 * Returns a value from a superglobal array corresponding to the
 * given key.
 *
 * Option: the key to look up within the superglobal array
 *
 * Also, it is possible that a superglobal variable is not populated by PHP
 * because of the settings in the variables-order ini directive. In this case
 * the converter will return an empty value.
 *
 * @see http://php.net/manual/en/language.variables.superglobals.php
 * @see http://www.php.net/manual/en/ini.core.php#ini.variables-order
 *
 * @package log4php
 * @subpackage pattern
 * @version $Revision: 1326626 $
 * @since 2.3
 */
abstract class LoggerPatternConverterSuperglobal extends LoggerPatternConverter
{

    /**
     * Name of the superglobal variable, to be defined by subclasses.
     *
     * For example: "_SERVER" or "_ENV".
     */
    protected $name;

    protected $value = '';

    public function activateOptions()
    {
        // Read the key from options array
        if (isset($this->option) && $this->option !== '') {
            $key = $this->option;
        }
        
        /*
         * There is a bug in PHP which doesn't allow superglobals to be accessed when their name is stored in a variable, e.g.: $name = '_SERVER'; $array = $$name; This code does not work when run from within a method (only when run in global scope). But the following code does work: $name = '_SERVER'; global $$name; $array = $$name; That's why global is used here.
         */
        global ${$this->name};
        
        // Check the given superglobal exists. It is possible that it is not
        // initialized.
        if (! isset(${$this->name})) {
            $class = get_class($this);
            trigger_error("log4php: $class: Cannot find superglobal variable \${$this->name}.", E_USER_WARNING);
            return;
        }
        
        $source = ${$this->name};
        
        // When the key is set, display the matching value
        if (isset($key)) {
            if (isset($source[$key])) {
                $this->value = $source[$key];
            }
        }         

        // When the key is not set, display all values
        else {
            $values = array();
            foreach ($source as $key => $value) {
                $values[] = "$key=$value";
            }
            $this->value = implode(', ', $values);
        }
    }

    public function convert(LoggerLoggingEvent $event)
    {
        return $this->value;
    }
}
